Drying gelatin capsules



May 19, 1953 F. E. s'rlRN ErAL 2,638,686

DRYING GELATIN CAPSULES Filed Nov. 21, 195o ATTORNEY Patented May 19,1953 DRYING'GELATIN CAPSULES vFrank Edwin Stirn, Evans Park, PearlRiver, and Arthur Sinclair Taylor, isprlngfvalley, N. Y., assignors toAmerican Cyanamid (lompany, New York, N. Y., a corporation of MaineApplication November 21, 1950, Serial No. 196,746

7 Claims.

1 i This invention has for its object-a method for the drying of softgelatin capsules in a particularly expeditious and economical mannerand,at the same time provides a method of insuringthat they are evenlyformed and fault-free.

-ln the past, gelatin capsules of `these-called soft variety have `beenmade by symmetrically assembling two mold shells together, at the sametime nlling themwith a liquid, pressing them firmly together withcutting-out rims to cut the gelatin sheets and simultaneously unite toform-a homogeneous, symmetrical, liquid-filled soft gelatin capsule.These capsules `were placed `on trays `in a single layer and `permittedto air-dry, after which they were packed in vials, `bottles, orotherwise counted, sorted, inspected, shipped-or disposed of. i

This entails theiuse of many individual trays, which trays of coursewere 'very-convenient for the inspection, counting, sorting andprocessing of small numbers of individual `pharmaceutical capsules. Whena large number of-capsules were to be filled, the use of Va large numberof trays be came economically ineicient, but Anonetheless were used.

With powder-nlled `soft `gelatin capsules, `in which a powdercharge ispacked `into a soft'gelatin shell, over which is placed va soft `gelatincover and the two vcut out to form a powderalled capsule, suena process`is. not satisfactory.

Because the powderis not capable of transferring` hydrostatic pressure,itis `found 'that uthe capsules as formed are apt to bemisshapen withthe powder unevely spaced, and thegelatinshell also distorted. We havefound that if the Apowder-nlled capsules are tumbled, or agitated, thepowder is shaken and then becomes Vmore freeilowing and by continualVpounding action, any irregularities are reduced so that 4a smooth,rounded, even capsule may be obtained. 'At the same time, the seal linemay shift until it is symmetrically on the capsule, if the hlm`temperatures and tensions are correct, and there are obtained smooth,evenly formed, perfectly shaped soft gelatin capsules. l

These moist capsules are extremely tender an are easily deformed orpressed out of shape. We have iound that it is particularly convenient`and economical to agitato the capsules in a rotating drum, a standard`pharmaceutical pan-coater being satisfactory for this purpose.

As the capsules are formed, they may be transfcrred by an air blast fromthe capsule filling machine to the rotatingdrum or pan. The tumblingthey receive duringfthe transfer partially aids in shaping them, andcauses them to become slightly air-dried, sufciently so that they do notas readily stick to each other. i Frequently'at `least `part of thecapsule is coated with an oil, and this also aids `in preventing thecapsules from sticking to each other.

The air blast from vthe conveyor keeps aconstant current of cool, dryair flowing through the drum. An -additional vblast of dry air may beVused but is normally unnecessary, The conveying blast can be directed soas to cause the capsules to be carried to the bottom of the pan.. As thepan rotates, and as they are tumbled, they progress towards the mouth ofthe pan, from which they may ylie permitted to freely Atali into singlelayer trays. By the time they fall into the trays, the capsules have asymmetrical shape, have a thin oil film,` and are suniciently air drythat they will not deform from their own weight or the `few inches fallinto a trayand may be permitted to fall into the tray in which they arespread by hand 4until a-single vlay-er 4covering substantially theentire tray is obtained. The filled tray may then be replaced by anempty tray and the iilledtray allowedl to dry. We prefer to stackthe-trayswith airncirculation spaces between, in atray drier.

In the tray drier, dry air 4is circulated over `the trays of capsules.Because of `the.drying'characteristics ofthe capsules, the amount ofmoisture that is lost in the rotating pan is comparatively high for thetime involved. The rate of moisture removal'in the tray drier is slower;but it is found that in a matter o approximately lf2 to 24 hours,

the capsules will `have been sufliciently dried to become iii-m, inwhich form they may be moved, if handled gently.

` If permitted to dry suiilciently for packing and handling, itis foundthat the .capsules must be permitted to remain in the tray drier at atemperature of approximately 65 lik-80 F. and a relative humidity ofless than about 40%, for not less `than 3-5 days. For small scaleproduction, this is satisfactory, but with large scale productio-n thespace occupied by the traydriers is cost- 1y. The amount'of moistureremoved in the last few days is only a .small proportion of the total,butnonetheless it must he removed to provide satisfactory capsules. i

We have found that after .approximately 12. to 24 hours `in the 'traydrier, thefcapsules are suf ciently Yrigid that they Willcnotdeform'ifplaced in baskets to a depth of Uwelveinches `or more.

The capsules may be dumped from the tray into the basket and permittedto stand in the basket, which is perforated to permit dry air tocirculate, for a period of about 3 to 5 days. In this manner, theduration of the expensive stage of tray drying is out to a minimum andthe capsules are stored in baskets, in which they do not occupy suchlarge spaces in the air-conditioned rooms and in which they may be keptafter they are dried for periods of weeks, or until used in the finalpackaging or finishing operations. The use of the three-stage dryingprocedure in which each stage is modified according to thecharacteristics of the capsules at that particular time, provides a veryefficient and economical method of drying our capsules. The process isshown diagrammatically in the drawings. Figure 1 shows the three stagesof drying at (a) drum drying, at (b) tray drying, at (c) basket drying,at (dra single layer of capsules in a tray. Figure 2 shows a detail ofthe basket nesting.

In the drawings, the pan-coater Il is rotated as the capsules l2 areintroduced by an air conveyor I3 and tumbled from the conveyor into thesingle layer tray M. As the second phase is shown in Figure l, b, a traydrier l5. The dry air supply lli and exit air Il are diagrammaticallyillustrated. As the third phase is shown in Figure l, c, a basket drieri8 showing how the baskets may be stacked to conserve space. Dry airiiows in through an inlet I9, through the stack of baskets and out thetop 2U.

At Figure 2 is shown a detail of basket con.. struction in which a bead2l lits into a groove 22 in the bottom of a basket to support the upperbaskets, and lock the stack. Other modifications may be used. The oneshown is neat, clean and economical.

The coating pan, tray drier and basket drier are all well known items ofequipment, and various modications and equivalents may be used. Ourinvention lies not in the individual components but in their combinationand the method of use.

A powder-filled capsule was manufactured,

containing an anemia preparation, from a gelatin film approximately3%000" thick. The capsules were approximately s in diameter and 1/2long. These capsules were tumbled `in an 18" diameter pan-coater intowhich the air conveyor introduced a large quantity of air at atemperature of approximately 65 F. and a relative humidity of about20-30%. The capsules as they were delivered therefrom fell into a singlelayer tray on which they were spaced so as to provide a single layer inwhich the capsules were adjacent to or touching each other withoutresting on or deforming the adjacent capsules. A tray 24 X 32 heldapproximately 1500 capsules. The trays were stacked in a tray drier,sufficient space being allowed to permit air to circulate between theadjacent trays. After 12 to 24 hours, the capsules were transferred tothe drying baskets. Baskets about 17" x 24 and 9" deep heldapproximately 15,000 capsules. They were stacked as the air wascirculated through the bottom of the baskets to evenly dry the cap-l '4three days', after which time the capsules were in their finished, hard,and dry condition.

The exact amount of drying in each of the stages may be varied overreasonable limits, depending upon the initial composition and the exacttemperatures being used; the gelatin is harderat lower temperatures andwill resist more handling, but a longer time is required for the drying.

Having thus described our invention in a manner to render it clear tothose skilled in the art, we claim:

1. The method of drying soft gelatin capsules which comprises tumblingsoft gelatin capsules until evenly formed and partially dried,transferring to single layer trays, spreading the capsules in a singlelayer therein, drying until sufficiently rm so as not to deform whenpacked in multi-layer packing, transferring to multilayer baskets, anddrying until hard.

2. The method of drying soft gelatin capsules which comprises the stepsof subjecting the soft gelatin capsules to cool, dry air whilesimultaneously tumbling the capsules for a suicient period to preventtheir sticking to each other, and to cause them to assume an even,rounded symmetrical configuration, transferring them to single layertrays, spreading the capsules in a single layer therein, subjecting themto dry air until sufficiently firm that they may be handled,transferring them to multi-layer baskets, and subjecting them to dry airuntil commerciallydry.

3. The method of drying soft gelatin capsules which comprises tumblingpowder-nlled soft gelatin capsules while simultaneously subjecting themto cool dry air until the capsules are sufiiciently rm not to stick toeach other and are symmetrically shaped, transferring them to fiatsingle layer trays, spreading the capsules in a single layer therein,subjecting to dry air until sufciently firm that they may be handled,and transferring them to multi-layer baskets, and subjecting them to dryair until commercially dry.

4. In a method for drying powder-containing soft gelatin capsules, thesteps which comprisetumbling powder-containing soft gelatin capsules inthe presence of dry air until evenly formed and partially dried,transferring to a single layer tray, spreading the capsules in a singlelayer therein, and subjecting the capsules to dry air until at leastsufficiently firm that the capsules may be convenientlyhandled.

5. The method of drying and shaping soft gelatin capsules whichcomprises tumbling soft gelatin capsules in a dry atmosphere untilevenly formed and partially dried, transferring to single layer trays,spreading the capsules in a single layer therein, drying untilsufficientlyv firm so as not' to deform when packed in multilayerbaskets, transferring to multi-layer baskets, and drying in said basketsuntil commercially dry.

6. The method of drying and shaping soft gelatin capsules whichcomprises tumbling soft gelatin capsules in a dry atmosphere untilevenly formed and partially dried, spreading the capsules in a singlelayer, contacting them with a d ry atmosphere until sufficiently rm soas not to deform when packed in multi-layer containers, transferring tomulti-layer containers, and drying in said containers until commerciallydry.

v 7. Iny a method for drying soft gelatin cap-` sules, the steps whichcomprise tumbling soft gelatin capsules in the presence of a dryatmosphere until evenly formed and partially dried, subsequentlyspreading the capsules in a single layer and contacting the capsuleswith a dry atmosphere until at least sufficiently rm that the capsulesmay be conveniently handled.

FRANK EDWIN STIRN. ARTHUR SINCLAIR TAYLOR.

6 References Cited in the le of this patent UNITED STATES PATENTS NumberName Date Baker Aug.. 12, 1924 Garnsey Sept. l, 1925 Brown Dec.` 11,1928 Dent et al. Jan. 26, 1943 Davis Feb.. 24, 1948 Sartorius Mar. 6,1951

